Plant interaction networks reveal the limits of our understanding of diversity maintenance

Species interactions are key drivers of biodiversity and ecosystem stability. Current theoretical frameworks for understanding the role of interactions make many assumptions which, unfortunately, do not always hold in natural, diverse communities. This mismatch extends to annual plants, a common model system for studying coexistence, where interactions are typically averaged across environmental conditions and transitive competitive hierarchies are assumed to dominate. We quantify interaction networks for a community of annual wildflowers in Western Australia across a natural shade gradient at local scales. Whilst competition dominated, intraspecific and interspecific facilitation were widespread in all shade categories. Interaction strengths and directions varied substantially despite close spatial proximity and similar levels of local species richness, with most species interacting in different ways under different environmental conditions. Contrary to expectations, all networks were predominantly intransitive. These findings encourage us to rethink how we conceive of and categorise the mechanisms driving biodiversity in plant systems.

Methods
This dataset was collected from a winter annual wildflower community at Perenjori Reserve in Western Australia. This is the same dataset as made available by Bimler et al. (2023a) at https://doi.org/10.5061/dryad.h44j0zpq3 but processed slightly differently.

Data collection is described extensively in Bimler et al. (2023b) and in the Methods and Supplementary Information S1.1 of the manuscript associated with this dataset, "Plant interaction networks reveal the limits of our understanding of diversity maintenance".

The dataset concerns a diverse and well-studied community of annual plants which grow, set seed and die within approximately 4 months every year. Individual fecundity data were collected in 2016 when 100 50 x 50 cm plots established in the understory of West Perenjori Reserve were monitored over the length of the full field season. 

References:

Bimler, Malyon; Mayfield, Margaret; Martyn, Trace; Stouffer, Daniel (2023a). Estimating interaction strengths for diverse horizontal systems using performance data [Dataset]. Dryad. https://doi.org/10.5061/dryad.h44j0zpq3

Bimler, M. D., Mayfield, M. M., Martyn, T. E., & Stouffer, D. B. (2023b). Estimating interaction strengths for diverse horizontal systems using performance data. Methods in Ecology and Evolution, 14, 968–980. https://doi.org/10.1111/2041-210X.14068